Multi-tenant network virtualization infrastructure

ABSTRACT

Some embodiments provide a method for a network management and control system that manages a virtual infrastructure deployed across a set of datacenters. Based on input from a top-level user of the virtual infrastructure, the method deploys a first logical network within the virtual infrastructure and defines one or more second-level users of the virtual infrastructure. The method receives input from a second-level user of the virtual infrastructure to define a second logical network and connect the second logical network to the first logical network. The first and second logical networks use a same data model and the second-level users are restricted from viewing configuration of the first logical network.

BACKGROUND

As more networks move to the cloud (public, private, or hybrid), it iscommon for application developers within a corporation or other entityto want to deploy applications that may span these sites. This presentsvarious challenges for the network administrators (e.g., the IT team fora corporation). In current systems, an application developer either hasto be made aware of the security and networking configurations in orderto deploy the application themselves, or work with the network admins tohave the application deployed within the network. Various solutions arerequired to solve these issues.

BRIEF SUMMARY

Some embodiments of the invention provide a network management systemfor managing a virtualization infrastructure having one or more logicalnetworks defined across one or more sites (e.g., datacenters). Thenetwork management system allows for a top-level user of the virtualinfrastructure (e.g., a cloud provider, an enterprise's networkadministrators) to define a provider logical network and to define oneor more second-level users (e.g., tenants, enterprise organizationalunits) of the virtualization infrastructure. These second-level userscan in turn define accounts for different users. Specifically, asecond-level user can define security and networking configuration(e.g., logical networking constructs, security zones) that is opaque tothird-level users (e.g., application developers) as well as othersecond-level users. Application developers can specify their applicationrequirements, without any knowledge of the security and networkingconfiguration, and the network management system of some embodimentsautomatically deploys the application according to the requirementswhile ensuring that the security and networking policies are adhered to.

As mentioned, the top-level user defines a provider logical network(this logical network will be referred to herein as a provider logicalnetwork irrespective of whether the top-level user is a cloud provider,enterprise network admin, etc.). In some embodiments, this providerlogical network is defined using a particular data model, such as ahierarchical policy tree with nodes and connections between the nodes.Through the data model, the top-level user can define security policiesand security groups as well as logical network elements (e.g., logicalrouters and/or logical switches). In addition, in some embodiments, theprovider data model includes a definition of the physical infrastructureonto which the virtualization infrastructure is deployed. This physicalinfrastructure of some embodiments may specify the multiple federatedsites across which the virtualization infrastructure is deployed, aswell as groups of physical elements within that site (e.g., groups ofedge devices that physically connect to external networks in each site,zones of physical servers and/or forwarding elements within each site).

The second-level users (referred to herein as tenants), in someembodiments, are granted the ability to define their own security andnetworking configuration, as well as to use certain entities exposed bythe provider network. Though these provider network entities may beexposed to tenant users, the tenant users are restricted from viewing orediting the configuration of the provider network (including theseentities). In addition, to provide isolation between users, one tenantuser is restricted from viewing (or modifying) the configuration of anyother tenant users. That is, each tenant is provided with the ability toview and modify only their own configuration, and not that of any othertenants or the higher-level provider user. Within a tenant'sconfiguration, sub-users can be created that can define their ownisolated configuration (which may be linked to the tenant or providerconfigurations, in some embodiments). Each of these isolatedconfigurations may be referred to as a virtual hybrid cloud (VHC); asdescribed further below, each VHC may be isolated to a single site orspread across multiple physical sites (e.g., a combination of enterpriseon-prem datacenters, branch offices, and public clouds).

In some embodiments, the data model for the tenant configuration issimilar to that for the provider configuration. That is, the tenantconfiguration is also represented (e.g., in storage of the networkmanagement system) as a hierarchical policy tree with similar nodes andconnections. One difference, however, is that in some embodiments onlythe provider user policy tree includes the physical infrastructure nodesdefining sites and groups of physical computing devices within a site.That is, some embodiments prevent the tenant users from both viewing orconfiguring the provider physical infrastructure nodes and from definingtheir own physical infrastructure policy.

In addition, the API is similar for the tenant user and for the provideruser when defining (e.g., creating, modifying) the same type of entity.For instance, the tenant administrator may define security policies andsecurity groups as well as logical network elements. In someembodiments, tenant users (and/or sub-users of the tenant) can define alogical network including logical switches to which data compute nodes(e.g., virtual machines (VMs), containers, etc.) connect and logicalrouters that connect these logical switches to each other. As describedfurther below, the data compute nodes (DCNs) may implement applicationsdeployed in the tenant logical network in some embodiments.

In some embodiments, logical routers can be either tier-0 (T0) logicalrouters that provide a connection to external networks or tier-1 (T1)logical routers that (i) connect logical switches to each other, (ii)provide services (e.g., firewall, load balancing, etc.), and (iii)enable connections to T0 logical routers. Some embodiments only allowthe provider user to define T0 logical routers, so that the provideruser (e.g., the enterprise IT team) can oversee all of the rulesregarding external connections to the virtualization infrastructure(e.g., routing protocols for route exchange with external routers,virtual private network (VPN) connections, etc.). The provider user candefine multiple virtual routing and forwarding tables (VRFs) for asingle T0 router in some embodiments. The tenant user, on the otherhand, can only define T1 logical routers in some embodiments. In otherembodiments, when a tenant user is created by the provider, an isolatedVHC is automatically created with a T0 VRF specific to the tenant. Thetenant user can manage this T0 VRF and define services such as routingprotocols (e.g., BGP, OSPF) and VPNs, while isolating this configurationfrom any sub-users.

All types of users (providers, tenants, sub-users) may define securitypolicy for their respective VHCs in some embodiments. This securitypolicy may include, in some embodiments, security rules (e.g.,distributed firewall rules and/or gateway firewall rules), securitygroup definitions, and domains. Domains, in some embodiments, arelogical groupings of one or more sites (e.g., within a similargeographic regions) that serve as an envelope to group different logicalentities together (e.g., for security purposes). For example, firewallpolicies or other policy micro-segmentation applied to the domain willautomatically be applied to all groups of logical endpoints definedwithin the domain in some embodiments. Security groups, in someembodiments, are groups of logical network endpoints that share one ormore attributes (e.g., operating system, region, application tier,etc.). The user (provider or tenant) can apply security rules to asecurity group, and the network management and control system translatesthese security rules into rules applied to each DCN in the securitygroup. In some embodiments, the security rules and groups are definedwithin domains.

While the tenant users cannot configure or view the configuration ofentities defined within the provider VHC, some embodiments allow theprovider user to expose some of these entities for use by the tenantusers. In some embodiments, the provider user exposes these entities toone or more tenants via labels, which allow the tenant user to identifythe type of entity and any specific properties of import, but not toview or modify the full configuration of the entity. For instance, aprovider user might expose a T0 logical router or simply a VRF of a T0logical router to which the tenant user (or its sub-users) can connecttheir T1 logical routers. The label might indicate the sites spanned bythe T0 logical router, but not the VLAN segments connected to the T0logical router or its routing protocol configuration. Other types ofentities that a provider user might expose via labels include securitygroups that the tenant user can use to define firewall rules (with thetenant user aware of the attributes that cause a DCN to belong to thesecurity group, but not the full membership of the group outside of thetenant VHC), edge clusters (a physical infrastructure grouping ofdevices for implementing centralized routing components of logicalrouters) that the tenant user can use for T1 logical routers, as well asservices such as load balancers.

As mentioned, in addition to being provided with the ability toconfigure their own isolated logical network and security policy in aVHC, each tenant user can define additional sub-users, who in turn candefine their own isolated logical network and security policy within aVHC. For instance, if a tenant is a line of business within anenterprise, then sub-users may be defined for different organizationalunits within that business line, etc. Similarly, if a tenant is a publiccloud tenant, then the sub-users might be different business lineswithin the scope of the tenant. In addition, tenant users (or sub-users)may define accounts for application developers. In some embodiments,application developer users may not view or configure their own logicalnetworking and security rules (i.e., they are not granted their ownVHC), but rather can define applications within the scope of aparticular VHC. The implementation of these applications within a VHC isdescribed further below.

Tenant users and their sub-users can also define security zones in someembodiments. In some embodiments, security zones are defined to governthe connectivity (or other security policies) of applications. That is,DCNs implementing an application are assigned to security zones, and theconnectivity and/or other security policies of the security zone areapplied to those DCNs. In some embodiments, the user defining a securityzone defines the span of that security zone in terms of sites (of theprovider's physical infrastructure), thereby restricting applications(or tiers of applications) assigned to the security zone to those sites.Examples of common security zones include a first zone that allowsconnections from external endpoints (often referred to as a DMZ), aswell as a second zone that does not allow connections from externalendpoints but does allow incoming connections from the first zone (oftenreferred to as a production zone, and with which back-end servers orapplication tiers may be associated).

As mentioned, application developer users can be provided with theability to define an application within a VHC, without the ability toview or edit the networking and security configurations for the VHC. Insome embodiments, application developers specify a set of connectivityrequirements for an application. Based on these requirements, thenetwork management and control system automatically assigns the DCNsthat implement the application to the security zones defined for theVHC.

The applications are defined as sets of application tiers in someembodiments. For instance, applications are commonly specified as 3-tierapplications, with a web tier of web servers that accept incomingconnections from external endpoints, an application tier, and a back-enddatabase tier. The network management and control system assigns each ofthese defined application tiers to one of the security zones defined forthe VHC based on the requirements (e.g., connectivity requirements). Forinstance, a web tier that requires incoming connections from externalclient endpoints would be assigned to the DMZ, while a back-end databasetier that requires incoming connections from the web tier but not fromexternal client endpoints would be assigned to the production zone.Applications might also specify connection requirements to othernon-application DCNs within the tenant network, such as backup servers.So long as these non-application DCNs are assigned to the appropriatesecurity zone (e.g., the production zone), the connections fromapplication DCNs are allowed (even if these non-application DCNs are ina different VHC than the application).

Each VHC spans a set of the sites of the physical infrastructure, andpart of the application specification in some embodiments is a set ofthe sites of the application's VHC across which to deploy theapplication. As described above, each application tier is assigned to asecurity zone, and that security zone spans a set of sites. Thus, eachapplication tier is assigned to a subset of the sites designated for theapplication that is the intersection of (i) the sites designated for theapplication and (ii) the sites to which the security zone for thatapplication tier is restricted. That is, the DCNs implementing theapplication tier are deployed within that subset of sites. If there isno overlap between the sites designated for an application and the sitesto which a security zone for a tier of the application is restricted,some embodiments generate an error and alert the application developeruser of the error so that the application developer can designate adifferent set of sites for the application.

As part of assigning application tiers to security zones, the networkmanagement and control system of some embodiments also automaticallypopulates various sets of firewall rules to implement the security zonesfor the application. For instance, for internal connections (e.g., forconnections from the DMZ to the production zone), some embodimentsautomatically populate distributed firewall rules to allow thesespecific connections. These distributed firewall rules are implementedby the internal physical infrastructure (e.g., managed forwardingelements and/or firewall modules in virtualization software of hostcomputers), as configured by the network management and control system.

In addition, if the application has connectivity to external networks(e.g., if the application requires connections from external endpointclients), some embodiments auto-populate gateway (edge) firewall rulesassociated with a centralized routing component of a logical router. Insome embodiments, these gateway firewall rules are arranged in sections.The firewall rules have relative priorities within a section, and thesections have different priorities as well, so that the highest priorityrule in the highest priority section is the highest priority ruleoverall. The primary (highest priority) section in some embodiments iscreated and managed by the user that governs the logical router—e.g.,the provider for a T0 logical router, or a tenant user for a T1 logicalrouter.

For applications that require incoming connections, the firewall rulesshould be configured to allow connections in for that application, butnot such that all incoming traffic is allowed at the gateway. Thus, someembodiments have a default rule denying incoming connections, butinclude a higher priority rule that specifies to skip (jump) to adifferent firewall rule section specific to the application if theincoming connection is directed to the application (e.g., based on adestination address and/or transport layer port in the packet, or adetermination that the packet is directed to a particular logical portof the logical router). The application-specific firewall rule sectionhas rules configured specifically for the application, typically alongwith another default rule denying connections that do not meet thespecific required characteristics for the application. For instance, theapplication firewall rules might allow any incoming connectionsaddressed correctly to the application, only allow incoming connectionsfrom certain addresses, etc.

In addition to assigning application tiers to security zones anddefining firewall rules for the applications, some embodimentsautomatically generate logical networking constructs based on theapplication definition. Specifically, some embodiments allow the userthat defines a VHC to define application association policies for theVHC. An application association policy, in some embodiments, specifieshow an application with tiers is translated into logical networkentities. For instance, an application association policy mightautomatically define a separate logical switch for each applicationtier, along with a T1 logical router that connects these new logicalswitches. If the T1 logical router has centralized services requiringthe use of an edge gateway, then some embodiments automatically use anedge device located in an edge cluster (part of the physicalinfrastructure nodes of the provider policy tree) associated with theVHC in which the application is defined. If the application requiresexternal connections (e.g., from external client endpoints or tointernal backup servers located in a different VHC), then someembodiments automatically connect the T1 logical router to a particularT0 logical router that is exposed to the VHC. Rather than defining aseparate logical switch for each tier, an application association policycould assign all of the tiers (i.e., all of the DCNs implementing thetiers) to the same logical switch. In this case, some embodimentsdifferentiate the tiers using compute expressions (e.g., assigning tagsor other metadata to the DCNs implementing the different tiers).

The preceding Summary is intended to serve as a brief introduction tosome embodiments of the invention. It is not meant to be an introductionor overview of all inventive subject matter disclosed in this document.The Detailed Description that follows and the Drawings that are referredto in the Detailed Description will further describe the embodimentsdescribed in the Summary as well as other embodiments. Accordingly, tounderstand all the embodiments described by this document, a full reviewof the Summary, Detailed Description, and the Drawings is needed.Moreover, the claimed subject matters are not to be limited by theillustrative details in the Summary, Detailed Description, and theDrawings, but rather are to be defined by the appended claims, becausethe claimed subject matters can be embodied in other specific formswithout departing from the spirit of the subject matters.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth in the appendedclaims. However, for purpose of explanation, several embodiments of theinvention are set forth in the following figures.

FIG. 1 conceptually illustrates an example of a hierarchical policy treefor a provider logical network that spans multiple sites.

FIG. 2 conceptually illustrates the relationships between differentusers and their respective configurations.

FIG. 3 conceptually illustrates a simple example of a hierarchicalpolicy tree for a sub-user logical network.

FIG. 4 conceptually illustrates an example set of nested users of anetwork management system and their different VHCs.

FIGS. 5-9 conceptually illustrate different methods for connectingtenant logical networking constructs in different VHCs to externalnetworks via a T0 logical router and its VRFs.

FIG. 10 conceptually illustrates a provider policy tree with certainentities exposed to tenants via labels.

FIG. 11 conceptually illustrates the consumption of the labels shown inFIG. 10 by two different tenant VHCs.

FIG. 12 conceptually illustrates a process of some embodiments fordeploying an application based on an application definition from anapplication developer user.

FIG. 13 conceptually illustrates definitions for two security zones fora VHC according to some embodiments.

FIG. 14 conceptually illustrates an example application definitionaccording to some embodiments.

FIG. 15 conceptually illustrates the security zone assignment for theapplication tiers defined in FIG. 14.

FIG. 16 conceptually illustrates a process of some embodiments forassigning DCNs that implement an application to security zones anddifferent sites of a virtualization infrastructure.

FIG. 17 conceptually illustrates a VHC defined across four sites.

FIGS. 18 and 19 conceptually illustrate the specification of applicationdefinitions for the VHC of FIG. 17.

FIG. 20 conceptually illustrates a process of some embodiments forautomatically generating security constructs, including firewall rules,relating to an application.

FIGS. 21 and 22 conceptually illustrate the use of firewall rules toallow and deny different traffic at a gateway.

FIG. 23 conceptually illustrates a process of some embodiments forgenerating logical networking constructs (e.g., logical switches and/orlogical routers) and their configuration based on the definition of anapplication.

FIG. 24 conceptually illustrates a set of application associationpolicies for a VHC according to some embodiments.

FIG. 25 conceptually illustrates an example set of logical networkelements defined in a policy tree for an application definition.

FIG. 26 conceptually illustrates a diagram showing the overallnetworking and security realization of a set of applications createdwithin a VHC.

FIG. 27 conceptually illustrates at least a portion of the data model ofthe network management and control system of some embodiments.

FIG. 28 conceptually illustrates an electronic system with which someembodiments of the invention are implemented.

DETAILED DESCRIPTION

In the following detailed description of the invention, numerousdetails, examples, and embodiments of the invention are set forth anddescribed. However, it will be clear and apparent to one skilled in theart that the invention is not limited to the embodiments set forth andthat the invention may be practiced without some of the specific detailsand examples discussed.

Some embodiments of the invention provide a network management systemfor managing a virtualization infrastructure having one or more logicalnetworks defined across one or more sites (e.g., datacenters). Thenetwork management system allows for a top-level user of the virtualinfrastructure (e.g., a cloud provider, an enterprise's networkadministrators) to define a provider logical network and to define oneor more second-level users (e.g., tenants, enterprise organizationalunits) of the virtualization infrastructure. These second-level userscan in turn define accounts for different users. Specifically, asecond-level user can define security and networking configuration(e.g., logical networking constructs, security zones) that is opaque tothird-level users (e.g., application developers) as well as othersecond-level users. Application developers can specify their applicationrequirements, without any knowledge of the security and networkingconfiguration, and the network management system of some embodimentsautomatically deploys the application according to the requirementswhile ensuring that the security and networking policies are adhered to.

These logical networks, in some embodiments, are conceptual networkstructures that the irrespective user accounts define through thenetwork management system. As mentioned, the top-level user defines aprovider logical network (this logical network will be referred toherein as a provider logical network irrespective of whether thetop-level user is a cloud provider, enterprise network admin, etc.). Insome embodiments, this provider logical network is defined using aparticular data model, such as a hierarchical policy tree with nodes andconnections between the nodes. Through the data model, the top-leveluser can define security policies and security groups as well as logicalnetwork elements (e.g., logical routers and/or logical switches). Inaddition, in some embodiments, the provider data model includes adefinition of the physical infrastructure onto which the virtualizationinfrastructure is deployed. This physical infrastructure of someembodiments may specify the multiple federated sites across which thevirtualization infrastructure is deployed, as well as groups of physicalelements within that site (e.g., groups of edge devices that physicallyconnect to external networks in each site, zones of physical serversand/or forwarding elements within each site).

FIG. 1 conceptually illustrates an example of such a hierarchical policytree 100 for a provider logical network that spans multiple sites. Insome embodiments, a root node 102 represents the overall providerlogical network configuration. Portions of the policy tree 100 representlogical network elements and their respective configuration, includinglogical forwarding elements (e.g., logical routers, logical switches,etc.). For logical network entities (e.g., logical network elementsand/or policies), when the provider user account creates a new logicalnetwork entity, the network management system creates one or more nodesin the policy tree 100 for the entity. As noted, these logical networkentities can include logical network elements that span one or moresites and logical network policies that apply to those elements, and theconnections in the policy tree represent relationships between the nodes(e.g., parent-child relationships, logical network connections, etc.).The hierarchical policy trees of some embodiments, as well as certaintypes of entities represented by these policy trees, are also describedin greater detail in U.S. patent application Ser. Nos. 16/906,925 and16/906,944, both filed Jun. 19, 2020, and both of which are incorporatedherein by reference.

The logical network elements represented in the policy tree includelogical forwarding elements (e.g. logical routers, logical switches,etc.). For example, in FIG. 1, the policy tree 100 includes a Tier-0(T0) logical router 105, a Tier-1 (T1) logical router 110, and a logicalswitch 145 (also referred to as an overlay segment). Differences betweenT0 and T1 logical routers will be explained further below; in short, T0logical routers in the provider logical network provide the connectionto external networks for the provider logical network (and in some casesfor many tenant logical networks), whereas T1 logical routers segregatea set of logical switches from the rest of the logical network and mayperform stateful services for logical network endpoints connected tothose logical switches.

The node for the T0 logical router 105 has a number of child nodes,including static route definitions 130 and locale services 135 and 140referencing different physical sites A and B. This means that the T0logical router 105 spans these two physical sites and has centralizedrouting components defined within these sites, as described furtherbelow by reference to the portion of the policy tree for these sites.Grand-child nodes are defined for interfaces 120 and 125 (e.g., uplinkinterfaces for external connections, service interfaces for third-partyservices) at each of these sites as well as an IPsec VPN 115 at site B.

The node for the T1 logical router 110 has a child node for the logicalswitch 145. In addition, this T1 logical router node 110 references theT0 logical router node 105 (the dashed arrow), indicating that the T1logical router 110 connects to the T0 logical router 105 in order forlogical network endpoints connected to the logical switch 145 tocommunicate with external endpoints (i.e., endpoints of other logicalnetworks that also connect to the T0 logical router or endpointscompletely external to the virtualization infrastructure). Though notshown for the sake of simplicity, many of the entities in the policytree 100 have various additional characteristics that define theconfiguration of the represented logical network entities, which may bedefined by the user or inherited from a parent entity. For instance,services such as DHCP may be defined for different logical forwardingelements, logical switches are assigned IP address ranges, etc.

In addition to the logical forwarding elements, the providerhierarchical policy tree 100 include nodes for physical entities,including nodes for each physical site (e.g., each datacenter in thevirtualization infrastructure). For example, in FIG. 1, there are nodesfor site A 160 and site B 177 under the global root node 102. Each sitehas a respective enforcement point child node 161 and 178, under whichspecific physical resources are assigned, such as edge clusters,transport zones, etc. This figure illustrates edge clusters 151 and 152at grand-child nodes of the site nodes 160 and 177, respectively. Insome embodiments, edge clusters are groups of edge devices that hostcentralized routing components of logical routers (e.g., forimplementing the connections with external networks, providingcentralized stateful services, etc.). This figure also illustrates atransport zone node 154 in site A. Transport zones, in some embodiments,are groups of transport nodes in a particular portion of a site (e.g., aparticular rack of servers). Transport nodes, in some embodiments,represent the entities of physical devices that are managed to implementthe logical network. For instance, in many cases, the transport nodesare hypervisors that execute virtual switches and/or virtual routers aswell as various distributed services (e.g., distributed firewalls).These managed forwarding elements and other managed network elementsimplement the logical forwarding elements (e.g., logical switches,distributed logical routers) as well as various logical networkpolicies.

In the illustrated example, the edge clusters 151 and 152 haverespective incoming references from locale services 135 and 140 attachedto the T0 logical router 105. In some embodiments, edge clusters alsohave children corresponding to specific edge nodes (e.g., the edge node153). In some embodiments, the network management system identifies thephysical structure of a site (and therefore the structure of the childnodes for the site in the policy tree 100) via auto-discovery, when thesite is added to the overall provider network represented by the globalroot node 102.

The provider network policy tree 100 also includes nodes forsecurity-related entities. In some embodiments, security policy is atleast partially organized by defining domains, which are logicalgroupings of one or more sites (e.g., geographic regions) that serve asan envelope to group different logical entities together (e.g., forsecurity purposes). Domains are defined and represented as nodes in thepolicy tree 100 beneath the global root 102. In this case, a singledomain node 170 is shown in the figure. Unlike sites (described below),which represent a physical construct, domains are a logical construct,which serve as an envelope to group different logical entities together(e.g., for security purposes). For example, firewall policies or otherpolicy micro-segmentation applied to the domain will automatically beapplied to all groups of logical endpoints defined within the domain insome embodiments.

Domains can represent a single physical site or multiple sites. In thisexample, the domain 170 corresponds to both of the sites A and B, andthus the domain enforcement point node 172 references both of the siteenforcement point nodes 161 and 178. Some embodiments place restrictionson how sites can be organized into logical domains. For instance, eachphysical site may be restricted to membership in (i) a single domaincontaining only that site and (ii) a single domain containing more thanone site. In addition, domains are only created as top-level nodesbeneath the global root node 102 (i.e., domains are not children ofother domains) in some embodiments. The provider user defines domainswithin the provider policy tree by selecting the sites that belong tothe domain.

In some embodiments, logical network endpoints at each site arelogically organized into security groups which can span multiple sites.These security groups are groups of logical network endpoints that shareone or more attributes (e.g., operating system, region, etc.). Servicemachines as well as the managed network elements executing on hostcomputers (the transport nodes) apply logical network policies (such asnetwork policy 173) to the data messages exchanged between endpointsbelonging to the security groups in some embodiments, based on policyrules that are defined in terms of these groups. In some embodiments,security groups and network policies are represented in the globalpolicy tree 100 as child nodes of domains, and accordingly inherit theirparent domain's span. In some embodiments, the span of a network policyis defined not only by its parent domain, but also by sites and/ordomains which are referenced by the policy. The logical network policiesin some embodiments include forwarding policies, service policies, andsecurity policies, and are applied in some embodiments to govern thebehavior of the logical forwarding elements. The policies can be childnodes of a logical network element node in some embodiments (e.g.,static routing policy configuration for a logical router).

As noted, FIG. 1 conceptually illustrates the hierarchical policy treefor a provider logical network (i.e., the logical network for atop-level user of the network management and control system). Thesetop-level users are also granted the ability to create second-levelusers (referred to herein as tenants) and grant these second-level usersthe ability to define their own security and networking configuration insome embodiments, as well as to use certain entities exposed by theprovider network. Though these provider network entities may be exposedto tenant users, the tenant users are restricted from viewing or editingthe configuration of the provider network (including these entities). Inaddition, to provide isolation between users, one tenant user isrestricted from viewing (or modifying) the configuration of any othertenant users. That is, each tenant is provided with the ability to viewand modify only their own configuration, and not that of any othertenants or the higher-level provider user. Within a tenant'sconfiguration, sub-users can be created that can define their ownisolated configuration (which may be linked to the tenant or providerconfigurations, in some embodiments). Each of these isolatedconfigurations may be referred to as a virtual hybrid cloud (VHC); asdescribed further below, each VHC may be isolated to a single site orspread across multiple physical sites (e.g., a combination of enterpriseon-prem datacenters, branch offices, and public clouds).

FIG. 2 conceptually illustrates the relationships between differentusers and their respective configurations. As shown, at the top level isthe configuration 205 for the provider user. In some embodiments, thenetwork management and control system has only a single top-levelprovider user. This user can define logical networking and securitypolicies as part of the configuration 205. In addition, unlike the otheruser configurations, the provider user configuration 205 includesphysical infrastructure as part of the policy tree. As shown in FIG. 1,this physical infrastructure definition may specify different sites aswell as groups of physical computing devices at each of those sites.

The provider user can also create one or more second-level (tenant)users, providing initial information and constraints for these users,and exposing certain entities from the provider logical network to thetenant user. For instance, if the provider user has multiple T0 logicalrouters, the provider user can associate a specific one (or more) ofthese T0 logical routers (or T0 virtual routing and forwarding tables(VRFs), as described below) with the tenant. The tenant can use these T0logical routers or T0 VRFs to provide external connectivity for thetenant logical network(s). The provider also associates one or more edgeclusters (of the physical infrastructure) with the tenant; this may be amanual or automatic association in different embodiments. The tenant canuse these edge clusters to host T1 logical router centralized routingcomponents, centralized services (e.g., stateful services), etc. Inaddition, the provider user may place certain constraints on the tenantuser, such as limiting the number of certain types of elements (e.g., amaximum number of T1 logical routers) or limiting the tenant logicalnetwork to a subset of sites of the overall physical infrastructure.

The tenant user can create their own configuration 210 through thenetwork management and control system, defining logical networking andsecurity policies. Unlike the provider user configuration 205, thetenant user configurations 210 (or 215) do not include any physicalinfrastructure; otherwise these user configurations are similar instructure to the provider user configuration. As shown in the figure,the tenant user is not able to view or modify the provider userconfiguration 205 via the network management system. As described inmore detail below, however, certain logical and/or physical entities(e.g., one or more T0 logical routers, one or more edge clusters) of theprovider user configuration 205 are exposed by the provider to thetenant user configuration 210. In addition, the tenant userconfigurations 210 and 215 are fully isolated from each other; that is,one tenant user has no ability to view, modify, or even necessarily beaware of any other tenant user configuration, even if they sharephysical infrastructure resources and/or the use of provider logicalnetwork entities.

Furthermore, as shown, tenant users can create additional sub-users. Asshown in FIG. 2, the first tenant user (having configuration 210)creates two sub-user accounts, which create their own configurations 220and 225. These sub-users can also define logical networking and securitywithin their configurations, similar to the tenant user. In someembodiments, upon creating these sub-users, the tenant user can provideassociations for the tenant with (i) provider constructs that theprovider user associated with the tenant and (ii) any tenant userconstructs. For instance, T0 logical router and edge clusterassociations may be provided to the sub-user so that the sub-user can,e.g., define T1 logical routers associated with a particular edgecluster and connect these T1 logical routers to the provider T0 logicalrouter without any requirement to use the logical network entities ofthe tenant configuration 210. In addition, any restrictions placed onthe tenant (e.g., restricting the number of certain types of logicalnetwork entities or the specific sites available to a tenant user) arepassed to the sub-user accounts and may be further restricted by thetenant user (e.g., if a tenant user is restricted to having a maximum offive T1 logical routers, they may create five different sub-users andallow each of these sub-users only a single T1 logical router).

In some embodiments, these sub-user accounts are organizedhierarchically. That is, each tenant can create one or more sub-users(referred to as organizational units in some embodiments), and thesesub-users can also create further sub-user accounts. Each of thesub-user accounts at any level can create their own isolated securityand networking configuration, referred to in some embodiments as avirtual hybrid cloud (VHC). In other embodiments, the tenant andorganizational units are containers for lower-level accounts, and onlythe accounts can create separate VHCs. As an example organization, theprovider user might be an IT team for an enterprise, with the sites overwhich the virtualization infrastructure is implemented being a set ofmain and branch offices of the enterprise. In this case, a tenant usermight be the network admin(s) for a line of business within theenterprise, and sub-users are defined for different organizational unitswithin that business line, etc. Similarly, if the provider user is apublic cloud provider with multiple datacenters and a tenant is a publiccloud tenant (e.g., an enterprise), then the sub-users might bedifferent business lines within the scope of the tenant.

In addition, some embodiments allow the tenants or sub-users to createapplication developer users. These users, as described in greater detailbelow, are not able to view or modify any logical networkingconfiguration (neither the configuration of the user that created theapplication developer user nor of any higher-level users) but can definerequirements for applications to be deployed in a particular VHC. Asshown in FIG. 2, the app developer user is created by one of thesub-users, and provides application requirements 230, which use thenetworking and security constructs (e.g., the VHC) of the sub-useraccount configuration 220. The application developer user concept allowsnetworking administrators to enable application developers to createapplications within the virtualization infrastructure without having toeither (i) provide access to the actual networking configuration for theapplication developer or (ii) manually create networking and securityconstructs tailored to each application deployed in the virtualizationinfrastructure.

In some embodiments, the data model for the tenant configuration (or forother sub-user configurations) is similar to that for the providerconfiguration. That is, the tenant configuration is also represented(e.g., in storage of the network management system) as a hierarchicalpolicy tree with similar nodes and connections. FIG. 3 conceptuallyillustrates a simple example of a hierarchical policy tree 300 for asub-user (e.g., a tenant user, a sub-user account) logical network(within a VHC). As with the provider policy tree 100, a root node 305represents the overall VHC created by the user. This policy tree 300includes a logical networking section as well as a security section.However, unlike the provider policy tree 100, the sub-user policy tree300 does not include physical infrastructure nodes defining sites andgroups of physical computing devices within a site (i.e., there are noedge cluster or transport zone nodes in the sub-user policy tree). Someembodiments prevent the tenant users or sub-users from both viewing orconfiguring the provider physical infrastructure nodes and from definingtheir own physical infrastructure policy.

On the logical networking side, the policy tree 300 includes a T1logical router node 310 with three connected logical switch nodes315-325. This T1 logical router node 310 is also shown as connecting toa T0 logical router node 105 that is part of the provider configuration.This T0 logical router 105 may be exposed to the tenant user (and thusits sub-users), enabling the user creating the VHC to connect to the T0logical router 105 without viewing or modifying its full configuration.If the T1 logical router represented by node 310 has centralizedcomponents (e.g., for providing stateful services) rather than onlyhaving a distributed component, then the node 310 in some embodimentswould also be associated with edge clusters in one or more sites (e.g.,via locale service sub-nodes, as is the case for the T0 logical router105 shown in FIG. 1).

The policy tree 300 also includes security-related nodes, with a domainnode 330 defining a domain. For simplicity, the links to one or moresite enforcement points (in the provider policy tree) are not shown inthis figure, but some embodiments do allow tenants and other sub-usersto define domains across one or more sites (though the sites for adomain are limited by the sites to which the VHC is restricted).

All types of users may define security policy for their respective VHCsin some embodiments. This security policy may include, in someembodiments, security rules (e.g., distributed firewall rules and/orgateway firewall rules), security group definitions, etc.

For simplicity, the links to one or more site enforcement points (in theprovider policy tree) are not shown in this figure, but some embodimentsdo allow tenants and other sub-users to define domains across one ormore sites (though the sites for a domain are limited by the sites towhich the VHC is restricted). Within this domain 330, the user hasdefined two security groups 335 and 340, as well as a security policy345 that includes a rule 350 referencing the two security groups 335 and340 (e.g., a rule allowing or denying traffic between Group A and GroupB).

Each VHC in a virtualization infrastructure (i.e., a set of datacenters)managed by a network management system has a similar data model. FIG. 4conceptually illustrates an example set of nested users of a networkmanagement system and their different VHCs. Though all of the VHCs areshown with the exact same structure, it should be understood that thisis an illustrative example and different VHCs in a virtualizationinfrastructure will typically have varying definitions even though thedata models are the same for all of the VHCs. Furthermore, the providerinfrastructure policy tree 405 is shown separately from the tenant VHCsand includes additional nodes representative of the physicalinfrastructure nodes in the policy tree 405.

The provider creates a tenant user 410 as described, and directly withinthe domain of this tenant user 410, one organizational unit 415 iscreated and one account 420 is created. In addition, within theorganization unit 415, that user creates an account 425. In someembodiments, any type of user may define a VHC, while in otherembodiments only “account” users may define a VHC (as is the case inthis example). In this case, the account user 425 defines two separateisolated VHCs 430 and 435, while the account 420 defines a single VHC440 that is isolated from the first two VHCs 430 and 435 (but shares thesame data model with both them and the provider policy tree 405). Thatis, a single account may define multiple VHCs (e.g., to deploy differentapplications).

The isolation between VHCs requires that entities in one VHC may not beassociated with entities in other VHCs, in some embodiments. That is,there should be no connections between the policy tree nodes for one VHCand those of another VHC (except that they may both be associated withthe same exposed entity from the provider logical network. While theVHCs are isolated, some embodiments allow some communication betweenendpoint DCNs in different VHCs (e.g., so that a DCN implementing anapplication in one VHC can access backup servers in a different VHC ofthe same tenant or sub-user). In some embodiments, when a user creates aVHC, before (or in addition to) defining the logical network, the userdefines capabilities of the VHC (e.g., services offered within the VHC)as well as the capacity of the VHC (e.g., the sites to which the VHC isrestricted, as well as various requirements related to the size, scale,latency, throughput, etc.). In accordance with having a similar datamodel for the respective configurations, the API is also similar for theprovider user and for the various sub-users when defining (e.g.,creating, modifying) the same type of entity.

As mentioned above, some embodiments only allow the provider user tocreate and configure T0 logical routers, and particular T0 logicalrouters or T0 VRFs can be associated with different tenants and theirVHCs. This allows the provider user (e.g., the enterprise IT team, acloud provider network admin) to oversee all of the rules regardingexternal connections to the virtualization infrastructure (e.g., routingprotocols for route exchange with external routers, virtual privatenetwork (VPN) connections, etc.). The provider user can define multiplevirtual routing and forwarding tables (VRFs) for a single T0 router insome embodiments. The tenant user, on the other hand, can only define T1logical routers in some embodiments.

The types of logical routers in some embodiments will be quicklydescribed in greater detail. In some embodiments, logical routers can beeither T0 logical routers that provide a connection to external networksor T1 logical routers that (i) connect logical switches to each other,(ii) provide services (e.g., firewall, load balancing, etc.), and (iii)enable connections to T0 logical routers. T0 logical routers aregenerally defined by the network management and control system to have adistributed routing component (DR) that is implemented in a distributedmanner and one or more centralized routing components (service routers,or SRs) that are implemented in a centralized manner by edge devices. T1logical routers may be entirely distributed (e.g., if no centralizedstateful services are defined for the T1 logical router) or maysimilarly have both a DR as well as one or more SRs. The details ofthese types of logical routers and logical routing components arefurther described in U.S. patent application Ser. No. 16/906,905, filedJun. 19, 2020, which is incorporated herein by reference.

The provider can expose external connectivity via a T0 logical router tothe tenant VHCs in a variety of different ways in some embodiments. Asnoted above, some embodiments allow for one or more VRFs (i.e.,independent routing tables to which packets may be assigned) to bedefined for a particular T0 logical router and for these VRFs to beexposed to the tenant users (or the T0 VRFs can be managed by the tenantuser), rather than exposing the T0 logical router itself. In someembodiments, the SR for a T0 logical router is configured to implementall of the VRFs for that T0 logical router, whether those VRFs aremanaged by the provider user or the tenant user. When a particular T1logical router is connected to a particular T0 VRF, outgoing packetsprocessed by the particular T1 logical router are sent to the T0 logicalrouter in some embodiments with indicators (e.g., within anencapsulation header) that the packets are from the particular T1logical router (e.g., based on a logical switch defined internally toconnect the two logical routers). Based on this indicator, the T0 SRapplies the correct VRF to the packets.

FIGS. 5-9 conceptually illustrate different methods for connectingtenant logical networking constructs in different VHCs to externalnetworks via a T0 logical router and its VRFs. For example, in FIG. 5,two different VHCs managed by the same tenant (possibly belonging todifferent accounts) share the same T0 VRF. In this example, the providerdefines both a T0 gateway logical router 500 and a VRF 505 for thislogical router, and exposes the VRF 505 to the tenant user. This tenantuser manages two VHCs 510 and 515, inside of which respective T1 logicalrouters 520 and 525 are defined. In this example, both of the T1 logicalrouters 520 and 525 (in different VHCs) connect to the T0 VRF 505.

FIG. 6 conceptually illustrates that two different VHCs managed bydifferent tenants may also connect to the same VRF in some embodiments,if exposed by the provider to both tenants. In this example, theprovider again defines both a T0 gateway logical router 600 and a VRF605 for this logical router, and exposes the VRF 605 to tenant users Aand B. Each of these tenant users manage their respective VHCs 610 and615, inside of which respective T1 logical routers 620 and 625 aredefined. In this example, both of the T1 logical routers 620 and 625 (indifferent VHCs managed by different tenants) connect to the T0 VRF 605.It should be noted that if two or more different tenants use the same T0VRF exposed by the provider, the provider should ensure that there is nooverlap in the IP addresses assigned to the different tenants, as anyoverlap could create confusion for the T0 VRF when handling incomingdata traffic.

FIG. 7 conceptually illustrates that the provider may expose differentVRFs of the same T0 logical router to different tenants, so that theVHCs managed by these tenants connect to the different VRFs. In thisexample, the provider defines a T0 gateway logical router 700 and twoVRFs 705 and 710 for this logical router. The first VRF 705 is exposedto tenant user A and the second VRF 710 is exposed to tenant user B.Each of these tenant users manage their respective VHCs 715 and 720,inside of which respective T1 logical routers 725 and 730 are defined.These T1 logical routers 725 and 730 connect to the respective T0 VRFs705 and 710 that are exposed by the provider user to their respectivetenants.

FIG. 8 conceptually illustrates that one or more tenants can manage theVRFs associated with a T0 logical router within their own VHCs (orwithin a different VHC managed by the tenant, depending on theconfiguration). In this example, the provider defines a T0 gatewaylogical router 800 and exposes this logical router 800 to the tenantusers A and B. Each of these tenant users manages their respective VHCs815 and 820, inside of which respective T1 logical routers 825 and 830are defined. In addition, each of the tenant users manages a respectiveT0 VRF 805 and 810. These VRFs may be automatically defined when thetenant users are created, or separately created and linked with the T0logical router 800 in different embodiments. While the previous examplesillustrate cases in which the provider entirely manages the T0 logicalrouter and T0 VRFs, in this example a T0 VRF is created specific to thattenant which can be managed by the tenant. It should be noted that whilethis example shows the T0 VRFs 805 and 810 in a VHC along with the T1logical routers 825 and 830 as well as logical switches, in someembodiments the tenant-managed T0 VRFs are automatically created for thetenants in an isolated VHC (i.e., separate from any other VHCs of thetenant). The tenant user can manage this T0 VRF and define services suchas routing protocols (e.g., BGP, OSPF) and VPNs. If the T0 VRF isconfigured in a separate VHC, this configuration is then isolated fromany sub-users, though the tenant user can also expose the T0 VRF to itssub-users for connecting to the T1 logical routers of their VHCs.

Finally, FIG. 9 conceptually illustrates that the provider may simplyexpose the T0 logical router itself to a tenant (or multiple tenants),without the use of VRFs at all (though in some such cases, the actualedge devices implementing the SRs for the T0 logical router may use oneor more VRFs to handle routing). In this case, the provider defines a T0gateway logical router 900 and exposes this logical router to a tenantuser. This tenant user manages two VHCs 905 and 910, inside of whichrespective T1 logical routers 915 and 920 are defined. In this example,both of the T1 logical routers 915 and 920 (in different VHCs) connectdirectly to the exposed T0 logical router 900.

While the tenant users cannot configure or view the configuration ofentities defined within the provider logical network, as indicated, someembodiments allow the provider user to expose some of these entities foruse by the tenant users. In some embodiments, the provider user exposesthese entities to one or more tenants via labels, which allow the tenantuser to identify the type of entity and any specific properties ofimport, but not to view or modify the full configuration of the entity.

FIG. 10 conceptually illustrates a provider policy tree 1000 withcertain entities exposed to tenants via labels. Similar to the policytree shown in FIG. 1, the provider policy tree 1000 includes a T0logical router node 1005 with one T0 VRF node 1010 defined (in additionto other child and grand-child nodes). The policy tree 1000 alsoincludes a node 1015 representing a domain, which includes a securitygroup 1020 and a defined network policy 1025. Finally, the physicalinfrastructure portion of the policy tree 1000 includes a site node 1030with grand-child nodes (underneath the site enforcement point) for atransport zone 1032 and an edge cluster 1035.

The figure also illustrates that a number of these entities are exposedto tenants via labels. Specifically, the T0 logical router 1005 isexposed via a label 1040, the T0 VRF 1010 is exposed via a label 1045,the edge cluster 1035 is exposed via a label 1050, and the securitygroup 1020 is exposed via a label 1055. The use of labels allows theprovider to expose the entities without exposing the configuration ofthe entity (i.e., the tenant cannot view the configuration of theexposed entity at all). The T0 logical router label 1040 or T0 VRF label1045 enables a tenant user to which these labels are exposed (or theirsub-users) to connect their T1 logical routers to these entities withoutviewing the logical router configuration. Such labels might indicate thesites spanned by the T0 logical router, but not the VLAN segmentsconnected to the T0 logical router or its routing protocolconfiguration. The edge cluster label 1050 might indicate the site atwhich the edge cluster is located, but not any details about the edgecluster that are available to the provider (e.g., the type or number ofedge devices in the cluster). Finally, the security group label 1055might indicate the attributes that cause a DCN to belong to the securitygroup, but not the full membership of the group outside of the tenantVHC. It should be noted that other types of entities may be exposed vialabels in some embodiments (e.g., services such as load balancers).

FIG. 11 conceptually illustrates the consumption of these labels1040-1055 by two different tenant VHCs. For simplicity, only relevantnodes of the policy trees 1105 and 1110 for these VHCs are shown in thefigure. The first VHC represented by root node 1115 includes a T1logical router represented by node 1120. This T1 logical router 1120 ispurely distributed (i.e., there are no services requiring centralizedrouting components for the T1 logical router 1120) and thus no edgecluster is required. However, the T1 logical router 1120 is connected tothe T0 logical router 1005 in the provider network via the label 1040.The second VHC represented by root node 1125 includes a T1 logicalrouter represented by node 1130 and a domain represented by 1135. Here,the T1 logical router 1130 requires centralized routing components andis therefore linked to the edge cluster 1035 via the label 1050. Inaddition, the T1 logical router 1130 is connected to the T0 VRF 1010 viathe label 1045. The T1 logical router 1120 in the first VHC connectsdirectly to the T0 logical router 1005, while the T1 logical router 1130in the second VHC connects to the T0 VRF 1010 because in this case theprovider exposes the T0 label 1040 to the tenant managing the first VHCand exposes the T0 VRF label 1045 to the tenant managing the second VHC.Lastly, the domain 1135 in the second VHC 1110 represented consumes thesecurity group 1020 via the label 1055, so that this security group 1055is part of the domain 1135 defined within the second VHC.

In addition to the types of users described above, in some embodimentstenant users or sub-users may define user accounts for applicationdevelopers. In some embodiments, these application developer users areassociated with a VHC, but may not view or configure the logicalnetworking and security rules of this VHC (i.e., these users are notgranted the ability to create a new VHC or view the configuration of theVHC with which they are associated). Rather these users can defineapplications within the scope of the associated VHC, and variouspolicies defined for the VHC enable the automated implementation ofthese applications without additional intervention by the user that ownsthe VHC.

FIG. 12 conceptually illustrates a process 1200 of some embodiments fordeploying an application based on an application definition from anapplication developer user. In some embodiments, the process 1200 isperformed by the network management and control system upon receiving anapplication definition for a particular VHC. The various differentoperations of the process 1200 will also be described in greater detailbelow. It should be understood that the process 1200 is a conceptualprocess, and that the operations shown in this process may be performedin a different order or in parallel.

As shown, the process 1200 begins by receiving (at 1205) a definition ofan application to be deployed in a particular VHC. The applicationdefinition, in some embodiments, specifies requirements for deploymentof a real-world application. These applications may include widely usedapplications such as SharePoint, Epic, or SAP, as well as single- ormulti-tier proprietary applications specific to a business's needs. Therequirements specified by the application definition may include, e.g.,connectivity requirements (e.g., whether external connectivity isrequired), service requirements (e.g., load balancers, etc.), and theset of available sites in which the application may be deployed (e.g.,if the application does not comply with Europe's general data protectionregulation (GDPR), it may only be deployed in North American sites),among other requirements. In some embodiments, as described furtherbelow, the application is defined in terms of a set of tiers (e.g., webtier, app tier, database tier), and the connectivity and otherrequirements for each tier.

The process 1200 then determines (at 1210) security zones into which theapplication is deployed. In some embodiments, the tenant users and theirsub-users (i.e., the owner of a VHC) can define security zones withinthe VHC. In some embodiments, security zones are defined to govern theconnectivity (or other security policies) of applications. That is, DCNsimplementing an application or application tier are assigned to securityzones, and the connectivity and/or other security policies of thesecurity zone are applied to those DCNs. Examples of common securityzones include a first zone that allows connections from externalendpoints (often referred to as a DMZ) as well as a second zone thatdoes not allow connections from external endpoints but does allowincoming connections from the first zone (often referred to as aproduction zone, and with which back-end servers or application tiersmay be associated). Some embodiments may also include a testing securityzone for applications in their testing phase (with minimal or noexternal traffic required at this point).

Next, the process 1200 determines (at 1215) the sites at which to deploythe application. In some embodiments, the user that defines a securityzone also defines the span of that security zone in terms of sites (ofthe provider's physical infrastructure), thereby restrictingapplications (or tiers of applications) assigned to the security zone tothose sites. The sites to which a security zone is restricted caninclude any of the sites to which the containing VHC is restricted, insome embodiments, but cannot include other sites that are not availablefor the VHC. An application can be deployed in any of the sites that are(i) specified for the application and (ii) available for the securityzone(s) to which the application is assigned. In some embodiments, thisdetermination is made on a tier-by-tier basis.

The process 1200 also determines (at 1220) the logical networking setupfor the application. Some embodiments automatically generate logicalnetworking constructs based on the application definition. Specifically,some embodiments allow the user that defines a VHC to define applicationassociation policies for the VHC. An application association policy, insome embodiments, specifies how an application is translated intological network entities. For an application defined with multiple tiers(which may also be referred to as application subnets, in some cases),an application association policy might automatically define a separatelogical switch for each application tier, along with a T1 logical routerthat connects these new logical switches. Rather than defining aseparate logical switch for each tier, an application association policycould also assign all of the tiers (i.e., all of the DCNs implementingthe tiers) to the same logical switch. In this case, some embodimentsdifferentiate the tiers using compute expressions (e.g., assigning tagsor other metadata to the DCNs implementing the different tiers).

The process 1200 also generates (at 1225) firewall rules for traffic toand from the application. In some embodiments, these firewall rulesimplement the security zones to which the application is assigned forthe traffic to and from the application. For instance, for connectionsinternal to the virtualization infrastructure (e.g., for connectionsbetween DCNs assigned to the DMZ and DCNs assigned to the productionzone), some embodiments automatically populate distributed firewallrules to allow these specific connections.

In addition, if the application has connectivity to external networks,some embodiments auto-populate gateway (edge) firewall rules to ensurethat these connections are allowed. In some embodiments, these gatewayfirewall rules are arranged in sections. The firewall rules haverelative priorities within a section, and the sections have differentpriorities as well, so that the highest priority rule in the highestpriority section is the highest priority rule overall. For applicationsthat require incoming connections, the firewall rules are configured toallow connections in for that application, but not such that allincoming traffic is allowed at the gateway. Thus, some embodiments havea default rule denying incoming connections, but include a higherpriority rule that specifies to skip (jump) to a different firewall rulesection specific to the application if the incoming connection isdirected to the application. The application-specific firewall rulesection has rules configured specifically for the application, typicallyalong with another default rule denying connections that do not meet thespecific required characteristics for the application.

Next, the process 1200 deploys (at 1230) DCNs implementing theapplication at the determined sites. In some embodiments, this operationis actually performed by a compute manager that is separate but works inconjunction with the network management system. The DCNs may be VMs,containers, or other types of DCNs in different embodiments, and aredeployed with software required to implement the application (or aspecific tier of the application). The deployment, in some embodiments,also enables these DCNs to attach to the appropriate logical ports ofthe logical switches (or other logical forwarding elements) to which theDCNs are connected according to the determined logical networkingconstructs for the application.

Finally, the process 1200 configures (at 1235) managed network elementsto implement the logical networking and firewall rules (and any othersecurity or other services required for the application). These managednetwork elements, as described above, include various elements executingin the hypervisors of the nodes to perform logical switching, logicalrouting, implementation of distributed firewall rules, etc. The managednetwork elements also include the edge devices that implement the T0 andT1 SRs and implement gateway firewall rules in some embodiments. Theprocess 1200 then ends.

As noted, tenant users and their sub-users are able to define securityzones through the network management system in some embodiments. Thesesecurity zones govern the connectivity or other security policies ofapplications, such that the connectivity and/or other security policiesof a security zone are applied to the DCNs assigned to that securityzone.

FIG. 13 conceptually illustrates definitions for two security zones 1300for a VHC according to some embodiments. These two security zonedefinitions include a DMZ definition 1305 and a production zonedefinition 1310. As shown, the DMZ definition 1305 specifies thatapplications (or application tiers) assigned to the DMZ are allowed toreceive ingress connections from external sources (e.g., from webclients). This connectivity is important for applications that allowusers to interact with the application via the Internet (e.g., without aVPN connection). In addition, the DMZ definition 1305 specifies thategress connections are allowed to DCNs assigned to the production zone.Similarly, the production zone definition 1310 specifies that ingressconnections are allowed from the DMZ, but that any connections withexternal sources are denied. Though only two security zones arespecified in this example, it should be understood that other types ofsecurity zones may be specified in some embodiments; for instance, atest security zone might not allow connections from outside the testzone (i.e., for use by applications during a testing phase).

It should be noted that, in this example, the security zones are definedat the same level for a particular VHC. In some embodiments, the networkmanagement system allows a user (e.g., a tenant user or sub-user, oreven a provider user) to define security zones that are available acrossall VHCs underneath that particular user. That is, a provider user coulddefine the DMZ security zone for all VHCs in the entire virtualizationinfrastructure. Similarly, a tenant could define a DMZ security zone (ifthe provider does not) for all VHCs belonging to the tenant and itssub-users.

While the security zones applicable to a VHC are defined by the VHCowner or higher-level users, the applications are defined by anapplication developer user. These applications are defined as sets ofapplication tiers in some embodiments, with requirements specified foreach tier. For instance, applications are commonly specified as 3-tierapplications, with a web tier of web servers that accept incomingconnections from external endpoints, an application tier, and a back-enddatabase tier.

FIG. 14 conceptually illustrates an example application definition 1400according to some embodiments. The application definition 1400 specifiestwo tiers, rather than a traditional three-tier application. These twotiers are a web tier 1405 and a backend tier 1410, and each tierspecifies its requirements. In some embodiments, from the applicationdeveloper perspective, an application tier is a set of workloads (e.g.,DCNs) that share common networking and security services. Theapplication definition 1400 specifies these required services for eachtier. In some embodiments, connectivity requirements are also specifiedas services. In this case, the web tier 1405 specifies that externalconnectivity (i.e., allowing ingress from external clients) and loadbalancing across the DCNs of the tier are required. The backend tier1410 specifies that connectivity with the web tier 1405 (i.e., allowingingress from web tier DCNs) is required, but does not specify any otherservices. Some embodiments might specify additional services such as webapplication firewall (WAF), intrusion detection and/or protectionsystems (IDS/IPS), etc.

In some embodiments, certain application service constructs areassociated with the VHC, and the application developer can choose fromthese services when specifying the requirements for an application to bedeployed in the VHC. These application service constructs may be exposedto the application developer as templates that indicate theconfiguration for a particular service (e.g., load balancing, etc.) witha combination of (i) pre-populated configuration elements that do notdepend on the application specification, (ii) configuration elementsthat are populated based on application properties, and (iii)configuration elements that are populated based on explicit applicationdeveloper input.

Upon receiving an application definition specifying one or moreapplication tiers for a particular VHC, the network management andcontrol system assigns each of these defined application tiers to one ofthe security zones defined for the particular VHC based on therequirements of the application (e.g., the connectivity requirements).FIG. 15 conceptually illustrates the security zone assignment 1500 forthe application tiers 1405 and 1410. In this example, the web tier 1405that requires incoming connections from external client endpoints isassigned to the DMZ 1305. The back-end tier 1410 that requiresconnectivity with the web tier 1410 but should not have any connectivitywith external client endpoints is assigned to the production zone 1310.It should be noted that application tiers might also specify connectionrequirements to other non-application DCNs within the tenant logicalnetwork, such as a set of backup servers. So long as thesenon-application DCNs are assigned to the appropriate security zone(e.g., the production zone), the connections from application DCNs areallowed (even if these non-application DCNs are in a different VHC thanthe application).

Each VHC is defined to span a set of the sites of the physicalinfrastructure, and part of the application specification in someembodiments is a set of the sites of the application's VHC across whichthe application can be deployed. In addition, the VHC owner (or otherhigher-level user) that defines a security zone defines the span of thatsecurity zone in terms of a set of sites to which the security zone isrestricted, thereby restricting application tiers assigned to thesecurity zone to those sites. Thus, each application tier is assigned toa subset of the sites designated for the application that is theintersection of (i) the sites designated for the application and (ii)the sites to which the security zone for that application tier isrestricted. That is, the DCNs implementing the application tier aredeployed within the subset of sites to which the application tier isassigned. If there is no overlap between the sites designated for anapplication and the sites to which a security zone for a tier of theapplication is restricted, some embodiments generate an error and alertthe application developer user of the error so that the applicationdeveloper can designate a different set of sites for the application

FIG. 16 conceptually illustrates a process 1600 of some embodiments forassigning DCNs that implement an application to security zones anddifferent sites of a virtualization infrastructure. The process 1600 isprimarily performed in some embodiments by a network management andcontrol system upon receiving an application definition, although asnoted above the actual deployment of DCNs may be performed by a computemanager (e.g., working in tandem with the network management system).The process 1600 will be described in part by reference to FIGS. 17-19,which illustrate the distribution of security zones across sitesassociated with a VHC and the assignment of example application tiers tothese sites.

Specifically, FIG. 17 conceptually illustrates that a VHC 1700 isdefined across four sites 1-4. Two security zones, a DMZ 1705 and aproduction zone 1710 are defined for this VHC 1700. The DMZ 1705 isrestricted to sites 1 and 2, while the production zone 1710 isrestricted to sites 2-4. These security zones 1705-1710 are definedaccording to the specification shown in FIG. 13 and will be used for theexamples shown in FIGS. 18-19 to more fully describe the process 1600.

As shown, the process 1600 begins by receiving (at 1605) a definition ofan application to be deployed in a particular VHC. The applicationdefinition, in some embodiments, specifies the tiers of the application,requirements for each tier of the application, and a set of sites acrosswhich the application can be deployed. In some embodiments, the sitesspecified for an application may only include sites with which theparticular VHC is associated (e.g., in the case of FIG. 17, only sites1-4 may be included in any application definitions for the VHC 1700). Asdescribed above, the applications may include widely used applicationsas well as proprietary applications specific to a business's needs. Therequirements specified by the application definition may includeconnectivity requirements (e.g., whether external connectivity isrequired) and/or other service requirements (e.g., load balancers,etc.).

FIGS. 18 and 19 conceptually illustrate the specification of applicationdefinitions 1800 and 1900, respectively. The application definition 1800specifies a web tier 1805 and a backend tier 1810, while indicating thatthe application can be deployed in sites 2 and 3. Meanwhile, theapplication definition 1900 specifies a web tier 1905 and a backend tier1910, while indicating that the application can be deployed in sites 3and 4.

Returning to FIG. 16, the process 1600 selects (at 1610) one of thespecified application tiers so as to assign the DCNs of that applicationtier to a security zone and identify the sites for the application tier.It should be understood that while this process 1600 individuallyassesses the tiers serially, this is merely a conceptual process. Theactual network management and control system of some embodimentsevaluates all of the tiers in parallel to assign the tiers to securityzones and determine the sites for each tier.

The process 1600 assigns (at 1615) the selected tier to a security zonebased on the requirements of the tier. In both of the examples, as inFIG. 14, the web tiers 1805 and 1905 are assigned to the DMZ 1705 whilethe backend tiers 1810 and 1910 are assigned to the production zone 1710based on their requirements (i.e., the web tier requiring externalconnectivity and the backend tier requiring connectivity with the webtier but no external connectivity).

Next, to determine the sites for the selected tier, the process 1600identifies (at 1620) the intersection of (i) the sites designated forthe application and (ii) the sites to which the assigned security zonefor the selected application tier is restricted. That is, eachapplication tier is restricted by two factors: the DCNs implementingthat tier can only be deployed in sites that are both (i) specified forthe application by the application developer and (ii) specified for thesecurity zone to which the tier is assigned by the user that defined thesecurity zone (e.g., the user that manages the VHC).

Based on this identification, the process 1600 determines (at 1625)whether there are any sites included in the intersection (i.e., whetheror not the intersection is the null set). If there are no sites thatsatisfy both of these criteria, then the process 1600 generates (at1630) an error. In FIG. 19, the web tier 1905 is assigned to the DMZ1705. However, the application definition specifies for the applicationto be deployed in sites 3 and 4, while the DMZ only spans sites 1 and 2.Accordingly, an error is returned to the application developer (e.g.,indicating that the connectivity requirements of the web tier requirethat the application include at least one of sites 1 and 2 in theapplication specification).

On the other hand, if at least one site satisfies both of the criteriafor the selected tier, then the process 1600 assigns (at 1635) theworkloads (e.g., the DCNs) for the tier to the identified site(s). FIG.18 illustrates that the web tier 1805 is assigned only to site 2, whilethe backend tier 1810 is stretched across sites 2 and 3. This is becausethe web tier 1805 is assigned to the DMZ 1705, which is restricted tosites 1 and 2 (with the application only assigned to site 2 among thesesites). Meanwhile, the backend tier 1810 is assigned to the productionzone 1710, which is restricted to sites 2-4 (with the applicationassigned to both site 2 and site 3 among these sites). Some embodimentsalways stretch each tier across all the sites to which the tier isassigned, while other embodiments employ various optimization algorithmsto determine whether each tier should be stretched across multipleavailable sites. For instance, when possible, some embodiments try toassign workloads to the sites in which all of the application tiersoverlap (e.g., site 2 in the example of FIG. 18). Other embodimentsallow for each tier to be stretched across all of its assigned sites butuse traffic optimization to determine to which site each actual DCN isdeployed.

Next, the process 1600 determines (at 1640) whether additional tiers ofthe application remain to be evaluated. If additional tiers remain, theprocess returns to 1610 to select the next tier. As noted previously,the process 1600 is a conceptual process, and some embodiments actuallyevaluate all of the tiers at the same time.

Once all of the tiers have been evaluated (and no errors are generated),the process 1600 deploys (at 1645) DCNs implementing each tier at thesites to which the tier workloads are assigned. In some embodiments,this deployment operation is actually performed by a compute managerthat is separate but works in conjunction with the network managementsystem. The DCNs may be VMs, containers, or other types of DCNs indifferent embodiments, and are deployed with software required toimplement the respective application tier. The deployment, in someembodiments, also enables these DCNs to attach to the appropriatelogical ports of the logical switches (or other logical forwardingelements) to which the DCNs are connected according to the determinedlogical networking constructs for the application, which is described inmore detail below.

As part of the process of assigning application tiers to security zones,the network management and control system of some embodimentsautomatically generates various sets of firewall rules in order toimplement the security zones for the application. These firewall rulesenforce the required ability or inability of DCNs in different securityzones to communicate with each other and/or with external sources. Insome embodiments, the firewall rules defined to implement security zonesfor an application include both distributed firewall rules (enforced bymanaged forwarding elements and/or firewall modules executing invirtualization software of host computers) and gateway firewall rules(enforced by the edge devices or firewalls connected to the edgedevices).

FIG. 20 conceptually illustrates a process 2000 of some embodiments forautomatically generating security constructs, including firewall rules,relating to an application. The process 2000 is primarily performed by anetwork management and control system in some embodiments upon receivingan application definition. It should also be understood that the process2000 describes only one possible set of security constructs that couldbe defined by the network management system to enforce the securityzones to which an application is assigned, and that other similarprocesses that define similar sets of security constructs are alsopossible in different embodiments.

As shown, the process 2000 begins by receiving (at 2005) a definition ofan application specifying the tiers of the application and theconnectivity (and other) requirements for each of the tiers. Asmentioned, some of these requirements are specified in terms ofapplication services that will be consumed by the application. In someembodiments, the application developer is required to provide values forcertain services according to application service templates

The process 2000 then assigns (at 2010) the tiers to security zones, asdescribed above (e.g., by reference to FIG. 16). These assignments arebased at least in part on the connectivity requirements specified foreach tier. Multiple tiers of an application might be assigned to thesame security zone (e.g., for a 3-tier application, the app tier anddatabase tier could both be assigned to a production security zone).Based on these assignments, as well as the application definition (e.g.,the different tiers), the process 2000 generates various securityconstructs.

The process 2000 defines (at 2015) a domain for the application in thepolicy tree of the VHC in which the application is defined. As describedabove, a domain in some embodiments is a logical construct that servesas an envelope for various security groups and policies. While theprocess 2000 described herein defines one domain for the application(with all of the security groups relating to the application), someembodiments define a separate domain for each of the services specifiedby the application.

In this case, within the domain, the process 2000 defines (at 2020)security groups for (i) the application and (ii) each tier of theapplication. A given DCN may belong to numerous different securitygroups. For instance, a DCN that is part of the web tier of anapplication could belong to a first security group for any DCNimplementing the application, a second security group for DCNsimplementing the web tier of the application, a third security groupincluding any DCNs executing a particular operating system, a fourthsecurity group for DCNs assigned to the DMZ (assuming that the web tieris assigned to this security zone), etc.

The process 2000 also defines (at 2025) distributed firewall rules toallow communication (i) between different application tiers that need tobe able to communicate with each other and (ii) between applicationtiers and other internal DCNs if this communication is required. In someembodiments, the distributed firewall rules specify to either allow ordeny specific traffic (e.g., from one or more source security groups toone or more destination security groups). Specifically, some embodimentsuse a whitelisting scheme, in which all traffic is assumed to be blockedunless specifically allowed by a firewall rule (e.g., by having adefault rule denying traffic that does not meet any other rule). As anexample of such a rule, traffic from the web tier of an application tothe database tier of that application can be allowed with a distributedfirewall specifying to allow traffic with the web tier security group asthe source and the database tier security group as the destination. Inaddition, certain applications may require connections with DCNsinternal to the virtualization infrastructure. For instance, aparticular tenant might setup backup servers for use by multipleapplications in a VHC or a set of VHCs. In some embodiments, thesebackup servers (or other services with which multiple applicationscommunicate) are created as a separate application, and distributedfirewall rules are defined so as to allow traffic between the backupservers and the application tiers that require connectivity with thebackup servers. In some embodiments, each connectivity requirement isspecified in terms of an application service that in turn specifies oneor more distributed (or gateway) firewall rules based on the applicationspecifics.

In addition, the process 2000 determines (at 2030) whether connectivitywith external sources is required. In some embodiments, thisconnectivity is specified as an application service requirement for aspecific tier of the application and invokes the creation of specificfirewall rules. Because this traffic passes through the T0 logicalrouter SR (i.e., the gateway at an edge device), some embodimentsgenerate gateway (edge) firewall rules (i.e., firewall rules associatedwith the SR) to allow certain traffic to (and from) the application.

If connectivity is required with external sources, the process defines(at 2035) a firewall rule application section (i.e., section of firewallrules specific to the application) for allowing specific traffic fromexternal sources to the application. In some embodiments, the gatewayfirewall rules (and, separately, the distributed firewall rules) arearranged in sections. The firewall rules have relative priorities withina section, and the sections have different priorities as well, so thatthe highest priority rule in the highest priority section is the highestpriority rule overall. The primary (highest priority) section in someembodiments is created and managed by the user that governs the logicalrouter—e.g., the provider for a T0 logical router, or a tenant user fora T1 logical router. In addition, some embodiments generate a sectionfor each security zone (e.g., a section for the DMZ, a section for theproduction zone, etc.), as well as a separate (lower-priority) sectionfor the application. Within the application section, the process 2000adds a rule allowing specific traffic from external sources (e.g., fromthe Internet, from any IP address, etc.) directed to the application. Incertain cases, this rule might use a public IP address used by theapplication, rather than the actual IP addresses of the web tier of theapplication, as this public IP address will be used in traffic processedby the T0 gateway (before performing network address translation on thetraffic). The rule allowing certain traffic might also be configured toonly allow connections from certain addresses, depending on thespecified connectivity requirement for the application. In addition, theapplication section typically includes a default rule specifying thatany other traffic that does not meet the specified criteria is to bedenied.

The process 2000 also defines (at 2040) a gateway firewall rule in theprimary section that jumps to the application section for traffic fromexternal sources directed to the application. This primary section mightbe the highest-priority application section managed by the provider aspart of the T0 gateway or could be a section associated with thespecific security zone that receives incoming connections (e.g., theDMZ). That is, this primary firewall rule section should not beconfigured to allow all incoming traffic received at the gateway, andtherefore has a default rule denying traffic. Rather than specificallyallowing traffic at a higher priority, a rule with a new type of actionskipping the rest of the section (and jumping to the applicationsection) is generated so that data traffic directed to the applicationis referred to the lower-priority application firewall rule section. Thedetails of whether to allow or deny such incoming traffic are thereforehandled by the rules generated for that section (at 2035). This new rulemight identify the incoming traffic for the application based on adestination address and/or transport layer port in the packet, or adetermination that the packet is directed to a particular logical portof the logical router associated with the application.

After generating the required firewall rules for the application, theprocess 2000 configures (at 2045) managed network elements to implementthe defined firewall rules. As noted previously, the distributedfirewall rules are implemented by the internal physical infrastructure(e.g., managed forwarding elements and/or firewall modules invirtualization software of host computers) of some embodiments, and thenetwork management and control system configures these elements to usethe newly generated firewall rules. Similarly, the edge devices thatimplement the T0 SRs also implement the gateway firewall rules in someembodiments, and the network management and control system alsoconfigures these edge devices and/or their associated edge firewalls.

FIGS. 21 and 22 conceptually illustrate the use of these rules to allowand deny different traffic at a gateway 2100. As shown, the gateway 2100implements a gateway firewall (in addition to implementing variouslogical forwarding elements and other services). The gateway firewall2105 may be executed by the same datapath that implements the logicalforwarding elements, a separate element, or even a separate (e.g.,third-party) device connected to the physical gateway edge device 2100,in different embodiments.

The gateway firewall 2105 includes firewall rules in at least twosections. The primary section 2110 includes a first rule specifying thatif the destination IP address of a data message is “App.Public.IP”(i.e., the public IP address used by a particular application), then theaction to be taken is to skip to the application section 2115 (withoutmaking a final decision on whether to allow or deny the packet). Theprimary section 2110 also includes a second rule that denies any otherincoming data messages. The application section 2115 includes a firstrule specifying that if the destination IP address of a data message is“App.Public.IP” and the destination transport layer port is “K”, thenthe data message should be allowed. That is, the applicationconnectivity requirements, as translated to firewall rules, require thatdata messages directed to the application also specify the correcttransport layer port K. The section 2115 also includes a default denyrule.

In FIG. 21, the gateway 2100 receives a data message 2120 with a sourceIP address A, destination IP address “App.Public.IP”, source transportlayer port J, and destination transport layer port K. During theprocessing of the data message 2120, the gateway firewall 2105 firstchecks the primary section 2110, and the data message 2120 matches thefirst rule. Accordingly, the gateway firewall 2105 skips to theapplication section 2115. Here, because the data message 2120 iscorrectly directed to the application (using the correct IP address andport number), the gateway firewall 2105 allows the data message.

In FIG. 22, the gateway 2100 receives a second data message 2200 with asource IP address A, destination IP address B, source transport layerport J, and destination transport layer port K. During the processing ofthe data message 2200, the gateway firewall 2105 first checks theprimary section 2110. Here, the data message 2200 does not match thefirst rule, and thus the second rule is applied to deny the datamessage. Thus, only data messages directed to the application IP addressare processed by the application section 2115; other data messages aredenied by the primary section 2110.

In addition to assigning application tiers to security zones anddefining firewall rules for the applications, some embodimentsautomatically generate logical networking constructs based on theapplication definition. Specifically, some embodiments allow the userthat manages a VHC (or a higher-level user) to define applicationassociation policies for the VHC. These application associationpolicies, in some embodiments, specify how an application definitionwith one or more tiers is translated into logical networking constructs(e.g., logical routers, logical switches, etc.).

FIG. 23 conceptually illustrates a process 2300 of some embodiments forgenerating logical networking constructs (e.g., logical switches and/orlogical routers) and their configuration based on the definition of anapplication. In some embodiments, the process 2300 is performed by anetwork management and control system upon receipt of an applicationdefinition from an application developer user. The process 2300 will bedescribed at least in part by reference to FIG. 24, which conceptuallyillustrates a set of application association policies, and FIG. 25,which conceptually illustrates the use of an application associationpolicy to generate logical forwarding elements based on an applicationdefinition.

As shown, the process 2300 begins by receiving (at 2305) a definition ofan application to be deployed in a VHC specifying one or more tiers andconnectivity requirements (as well as other types of requirements) foreach of the tiers. As described above, the application definition ofsome embodiments specifies the number of tiers, connectivity and otherservice requirements for each tier, and other information. In someembodiments, if the application is a common application type (e.g.,Epic, SharePoint, etc.), the application developer user may use atemplate provided by the network management system for the applicationthat uses a standard set of tiers and requirements for the applicationtype, with minimal customization. If the application is a proprietaryapplication, then some embodiments require additional customization(e.g., the number of tiers, specific connectivity requirements) from theapplication developer.

Based on the application definition, the process 2300 determines (at2310) an appropriate application association policy of the VHC in whichthe application is to be deployed to use for generating logicalnetworking constructs for the application. In some embodiments, themanager of the VHC affiliates one or more application associationpolicies (which may be pre-defined for the system or generated by theuser that manages the VHC) with the VHC. Different applicationassociation policies may specify different logical networking constructsbased on the number of tiers in the application (e.g., differentpolicies for 2-tier and 3-tier applications), whether the application isa specific type of application (e.g., there might be a first policy forSharePoint applications, a second policy for blog applications, etc.),or based on other factors.

FIG. 24 conceptually illustrates a set of application associationpolicies 2400 for a VHC according to some embodiments. The applicationassociation policies 2400, in this case, include two different policies2405 and 2410 for two different types of applications. As shown, each ofthese application association policies specifies instructions forgenerating and configuring logical forwarding elements to which logicalnetwork endpoints (DCNs) implementing the applications connect.

The first application association policy 2405 (for Type 1 applications)specifies to create a separate segment (e.g., logical switch) for eachtier of the application and to use IP address ranges available to theVHC to assign subnets for each of these segments. That is, the VHC willhave been assigned a set of private IP addresses (e.g., by the tenantuser that creates the VHC or creates the user that creates the VHC) tobe used for the DCNs in the VHC for communication internal to thevirtualization infrastructure. The application association policyspecifies to select a subnet from within this set of IP addresses toassociate with the logical switch; DCNs added to the logical switch willbe assigned an IP address from within the subnet. The applicationassociation policy 2405 also specifies to create a T1 logical router towhich each of the newly created segments attaches. Assuming that atleast one edge cluster in the physical infrastructure has beenassociated with the VHC, the application association policy 2405specifies for this edge cluster to be selected for hosting the SR(s) forthe T1 logical router. Finally, the application association policy 2405specifies for the T1 logical router to be connected to the T0 logicalrouter or T0 VRF (e.g., of the provider network) that is associated withthe VHC in which the application is deployed.

The second application association policy 2410 (for Type 2 applications,which in this case do not require external connectivity and may alsohave other specific properties) specifies to create a single segment forall tiers of the application and to use an IP address range available tothe VHC to assign a subnet for the segment. That is, for theseapplications, all of the DCNs implementing any of the application tiersare connected to the same logical switch. In this case, some embodimentsdifferentiate the tiers using compute expressions associated with theDCNs, so that the DCNs can still be easily assigned to differentsecurity groups for the different tiers. For instance, differentembodiments have the compute manager assign tags or other metadata tothe DCNs that indicate to which tier each DCN belongs. Other embodimentsuse specific IP addresses within the logical switch subnet todifferentiate the tiers. As shown, a T1 logical router is still createdaccording to the second application association policy 2410. Inaddition, the logical switch is still connected to this T1 logicalrouter and an edge cluster associated with the VHC is selected to hostthe SR(s) for the T1 logical router. The T1 logical router is notconnected to any T0 logical router or VRF in this case, as externalconnectivity is presumably not needed. This application associationpolicy 2410 could be used for applications in a testing phase in someembodiments.

Returning to FIG. 23, the process 2300 creates (at 2315) one or moresegments (logical switches) for the application tiers and assigns IPranges to the segments. In some embodiments, depending on theapplication association policy identified for the applicationdefinition, either one logical switch may be defined for each tier or asingle logical switch is defined for the application as a whole (that isshared between the tiers). As mentioned, if a single logical switch isdefined, then some embodiments differentiate the tiers using computeexpressions associated with the DCNs, so that the DCNs can still beeasily assigned to different security groups for the different tiers.

The process 2300 also creates (at 2320) a T1 logical router to connectthe one or more segments created for the application tiers and assignsone or more edge clusters for the T1 gateway (i.e., the T1 SR). Itshould be noted that if no centralized services are required for the T1logical router (e.g., if the only purpose of the T1 logical router is toconnect the logical switches), then the T1 logical router may beentirely distributed and no edge cluster assignment is required.

The process 2300 then determines (at 2325) whether connectivity withexternal sources is required. It should be noted that the process 2300is a conceptual process, and in some embodiments this determination ispart of the determination as to the appropriate application associationpolicy. That is, whether or not connectivity is required goes intodetermining the application association policy, and the logicalnetworking constructs to be generated are simply specified by thatpolicy.

When external connectivity is required for the application (e.g., for aparticular tier of the application), the process 2300 connects (at 2330)the T1 logical router created for the application to the T0 logicalrouter or T0 VRF that is assigned to the VHC in which the applicationwill be deployed. Whether the T0 logical router or one of multiple VRFsassociated with the T0 logical router is assigned to the VHC depends onwhich entities are exposed to the tenant by the provider (and, in turn,which entities the tenant assigns to the sub-user that manages the VHCif the VHC is not directly managed by the tenant user).

FIG. 25 conceptually illustrates an example set of logical networkelements defined in a policy tree 2500 for an application definition2505. As shown, the application definition 2505 specifies a web tier2510, an app tier 2515, and a database tier 2520. This applicationcorresponds to a Type 1 application (i.e., to the applicationassociation policy 2405), which may be indicated explicitly ordetermined based on the application properties.

Based on the application association policy 2405, the network managementsystem defines a set of logical network structures that are shown in thepolicy tree 2500. It should be understood that this policy tree is notcomplete, as it does not show either (i) the security constructs definedfor the application or (ii) any other logical networking constructsdefined within the VHC (e.g., for other applications). Underneath itsroot node 2525, the policy tree 2500 includes a T1 logical router node2530 and three logical switch nodes 2535-2545, with each logical switchcorresponding to a different tier of the application. In addition, someembodiments define a DHCP service 2550 associated with the T1 logicalrouter for the application. This DHCP service operates (e.g., at theedge cluster with which the T1 logical router 2530 is associated) toassign IP addresses to the DCNs implementing the application tiers thatconnect to any of the logical switches 2535-2545. Lastly, the T1 logicalrouter is connected to a T0 logical router represented by node 2555,which is part of the provider network but exposed to the VHC representedby the policy tree 2500.

Returning to FIG. 23, the process 2300 configures (at 2335) managednetwork elements within the virtualization infrastructure to implementthe logical networking constructs. As noted previously, the logicalforwarding elements are implemented by the internal physicalinfrastructure (e.g., managed forwarding elements, such as virtualswitches and virtual routers executing in virtualization software ofhost computers) of some embodiments, and the network management andcontrol system configures these elements to process data traffic to andfrom the application DCNs according to the newly-defined logicalforwarding elements. Similarly, the edge devices that implement the SRsfor the T1 logical router (if such an SR is created) and the T0 logicalrouter (if the T1 logical router is connected to a T0 logical router orT0 VRF) are also configured to implement these logical forwardingelements in their datapaths.

FIG. 26 conceptually illustrates a diagram 2600 showing the overallnetworking and security realization of a set of applications createdwithin a VHC. The diagram 2600 illustrates the different users thatmanage different aspects of the VHC and applications, as well as thesecurity groups/policies and logical networking constructs defined forone of the applications. As shown, in the provider space that isgoverned by the provider administrator user (i.e., the highest-leveluser of the network management and control system managing thevirtualization infrastructure), the DMZ security zone 2605 is created.In some embodiments, a provider security administrator defines thissecurity zone 2605, which may be used by not only the VHC 2610 shown inthe figure but also other VHCs of the same or other tenants. The DMZsecurity zone 2605 is restricted to sites 1-3 by the provider securityadministrator in this case.

The VHC 2610 is managed by a VHC administrator (e.g., a tenant, asub-user of the tenant, etc.), and is defined to span all of sites 1-4.In addition to the DMZ security zone 2605 associated with the VHC, a VHCsecurity administrator (which may be the same as the VHC administratoror a specific security admin user created by the VHC admin) defines aproduction security zone 2615 which is restricted to sites 2-4. Unlikethe DMZ security zone 2605, the production security zone 2615 isspecific to the VHC 2610.

Within the VHC, two different applications 2620 and 2625 have beencreated by two different application owners. The first application 2620is a three-tier application with a web tier (assigned to the DMZsecurity zone 2605, as shown by the dash-dot border), an app tier, and adatabase tier (both of which are assigned to the production securityzone 2615, as shown by the long-dash border). Three workloads (e.g.,VMs, containers, etc.) implement the web tier and load balancing is usedto distribute traffic between these workloads, two workloads implementthe app tier, and one workload implements the database tier. The secondapplication 2625 is a two-tier blog application with a web tier(assigned to the DMZ security zone 2605) and a backend tier (assigned tothe production security zone 2615). Three workloads implement the webtier and load balancing is again used to distribute traffic betweenthese workloads, while a single workload implements the backend tier.

The bottom portion of the diagram 2600 shows the security realization2630 and connectivity realization 2635 for the three-tier application2620. In this example, security groups are defined for (i) the databasetier of the application, (ii) the app tier of the application, (iii) theweb tier of the application, (iv) the application itself (a group thatwould include all workloads in any of the application tiers), (v) theDMZ security zone (i.e., any workloads assigned to this security zone),and (vi) the production security zone. The first four groups arerelevant only to this application, and corresponding security groupswould be created for the second application 2625 (not shown), while thelast two groups corresponding to the security zones are applicable toany other applications deployed in the VHC.

In addition, the security policies are broken down into differentsections, shown in order of priority. The highest-priority section isthe DMZ section (which includes a rule for each of the applications toskip to the application-specific sections for data traffic betweenexternal endpoints and the web tier workloads for those applications),followed by the production section, and then the twoapplication-specific sections of security policies.

The connectivity realization 2635 shows the logical networkingconfigured for the three-tier application 2620. In this case, the threeworkloads of the web tier are attached to a first segment (logicalswitch), the two workloads of the app tier are attached to a secondsegment, and the single workload of the database tier are attached to athird segment. Each of these segments is connected to a T1 logicalrouter defined for the three-tier application, which in turn connects toa T0 logical router (presumably managed by the provider).

Finally, FIG. 27 conceptually illustrates at least a portion of the datamodel 2700 of the network management and control system of someembodiments. This data model 2700 defines how logical networking andsecurity constructs, as well as security zones and applications may bedefined within the network management and control system. As shown,underneath the root, there is both (i) a provider section 2705 and (ii)a tenant section 2710. The provider section 2705, managed by theprovider user(s), allows the provider to define (under the infra rootnode) logical networking constructs, including T0 logical routers and T0VRFs belonging to those logical routers. For security aspects, theprovider user can define domains containing security policies (with oneor more rules) and security groups. In addition, some embodiments allowthe provider user to define services (e.g., layer 7 services), whichsecurity rules can reference.

The provider user also creates the tenant user 2715, which manages thetenant section 2710 and specifies the physical sites that the tenant mayuse. It should be understood that any number of tenant users, eachmanaging their own sections, may be created by the provider user. Thetenant may specify any number of sub-users, in this case organizationalunits. Either the tenant directly or these organizational units mayspecify account sub-users (e.g., the account 2720), and the creator ofthis account specifies the physical sites that the account may use forits one or more VHCs. The tenant user can also specify one or moreshared security zones (e.g., a DMZ) that are shared across allorganization units and/or accounts created underneath the tenant, aswell as an application service template for connectivity, loadbalancing, or other services. As described, the application servicetemplates define the configuration (possibly according to details froman application developer) for a service consumed by an application tier,such as external connectivity, communication with backup servers, loadbalancing, IDS/IPS, etc.

The account user 2720 can also define a VHC 2725, which may beconfigured by the account user 2720 or a separate VHC admin. Within aVHC 2725, the account user 2720 or the VHC admin can define securityzones (in addition to the shared security zones defined at the tenantlevel) and restrict these security zones to certain sites (so long asthose sites are within the purview of the VHC). The account user 2720 orVHC admin can also define application association policies for the VHCthat specify how to turn application definitions into logical networkingconstructs.

An application owner (application developer) governs their applicationdefinition 2730, which is under the purview of the VHC 2725. Theapplication owner specifies the application, indicating the sites atwhich the application can be deployed, as well as one or moreapplication tiers. For each application tier, application services maybe invoked for consumption by the tier by reference to applicationservice templates defined by the tenant. Each application tier isautomatically associated with a security zone, either one that isdefined within the VHC (as in this case) or that is shared between VHCs.In addition, an application association policy is used to generatelogical networking constructs (e.g., T1 logical routers, segments) underthe root node (infra) for the VHC policy tree definition. This policytree also includes IP assignment information (IP pools and IP blocks) aswell as the security information (domains, security policies with rules,and security groups) either specified by the VHC admin (or otherhigher-level user) or automatically generated based on the definition ofan application for the VHC. The security policy rules in the VHC canrefer to services and/or security groups defined within the VHC and/ordefined within the provider policy tree. Similarly, security ruleswithin the provider network can refer to services and/or security groupsthat are defined within the provider policy tree and/or a VHC. Theserules can specify the security groups as sources and/or destinations oftraffic and indicate whether or not such traffic should be allowed.

FIG. 28 conceptually illustrates an electronic system 2800 with whichsome embodiments of the invention are implemented. The electronic system2800 may be a computer (e.g., a desktop computer, personal computer,tablet computer, server computer, mainframe, a blade computer etc.),phone, PDA, or any other sort of electronic device. Such an electronicsystem includes various types of computer-readable media and interfacesfor various other types of computer-readable media. Electronic system2800 includes a bus 2805, processing unit(s) 2810, a system memory 2825,a read-only memory 2830, a permanent storage device 2835, input devices2840, and output devices 2845.

The bus 2805 collectively represents all system, peripheral, and chipsetbuses that communicatively connect the numerous internal devices of theelectronic system 2800. For instance, the bus 2805 communicativelyconnects the processing unit(s) 2810 with the read-only memory 2830, thesystem memory 2825, and the permanent storage device 2835.

From these various memory units, the processing unit(s) 2810 retrieveinstructions to execute and data to process in order to execute theprocesses of the invention. The processing unit(s) may be a singleprocessor or a multi-core processor in different embodiments.

The read-only-memory (ROM) 2830 stores static data and instructions thatare needed by the processing unit(s) 2810 and other modules of theelectronic system 2800. The permanent storage device 2835, on the otherhand, is a read-and-write memory device. This device 2835 is anon-volatile memory unit that stores instructions and data even when theelectronic system 2800 is off. Some embodiments of the invention use amass-storage device (such as a magnetic or optical disk and itscorresponding disk drive) as the permanent storage device 2835.

Other embodiments use a removable storage device (such as a floppy disk,flash drive, etc.) as the permanent storage device 2835. Like thepermanent storage device 2835, the system memory 2825 is aread-and-write memory device. However, unlike storage device 2835, thesystem memory 2825 is a volatile read-and-write memory, such asrandom-access memory. The system memory 2825 stores some of theinstructions and data that the processor needs at runtime. In someembodiments, the invention's processes are stored in the system memory2825, the permanent storage device 2835, and/or the read-only memory2830. From these various memory units, the processing unit(s) 2810retrieve instructions to execute and data to process in order to executethe processes of some embodiments.

The bus 2805 also connects to the input and output devices 2840 and2845. The input devices 2840 enable the user to communicate informationand select commands to the electronic system 2800. The input devices2840 include alphanumeric keyboards and pointing devices (also called“cursor control devices”). The output devices 2845 display imagesgenerated by the electronic system. The output devices 2845 includeprinters and display devices, such as cathode ray tubes (CRT) or liquidcrystal displays (LCD). Some embodiments include devices such as atouchscreen that function as both input and output devices.

Finally, as shown in FIG. 28, bus 2805 also couples electronic system2800 to a network 2865 through a network adapter (not shown). In thismanner, the computer can be a part of a network of computers (such as alocal area network (“LAN”), a wide area network (“WAN”), or an Intranet,or a network of networks, such as the Internet. Any or all components ofelectronic system 2800 may be used in conjunction with the invention.

Some embodiments include electronic components, such as microprocessors,storage and memory that store computer program instructions in amachine-readable or computer-readable medium (alternatively referred toas computer-readable storage media, machine-readable media, ormachine-readable storage media). Some examples of such computer-readablemedia include RAM, ROM, read-only compact discs (CD-ROM), recordablecompact discs (CD-R), rewritable compact discs (CD-RW), read-onlydigital versatile discs (e.g., DVD-ROM, dual-layer DVD-ROM), a varietyof recordable/rewritable DVDs (e.g., DVD-RAM, DVD-RW, DVD+RW, etc.),flash memory (e.g., SD cards, mini-SD cards, micro-SD cards, etc.),magnetic and/or solid state hard drives, read-only and recordableBlu-Ray® discs, ultra-density optical discs, any other optical ormagnetic media, and floppy disks. The computer-readable media may storea computer program that is executable by at least one processing unitand includes sets of instructions for performing various operations.Examples of computer programs or computer code include machine code,such as is produced by a compiler, and files including higher-level codethat are executed by a computer, an electronic component, or amicroprocessor using an interpreter.

While the above discussion primarily refers to microprocessor ormulti-core processors that execute software, some embodiments areperformed by one or more integrated circuits, such asapplication-specific integrated circuits (ASICs) or field-programmablegate arrays (FPGAs). In some embodiments, such integrated circuitsexecute instructions that are stored on the circuit itself.

As used in this specification, the terms “computer”, “server”,“processor”, and “memory” all refer to electronic or other technologicaldevices. These terms exclude people or groups of people. For thepurposes of the specification, the terms display or displaying meansdisplaying on an electronic device. As used in this specification, theterms “computer-readable medium,” “computer-readable media,” and“machine-readable medium” are entirely restricted to tangible, physicalobjects that store information in a form that is readable by a computer.These terms exclude any wireless signals, wired download signals, andany other ephemeral signals.

This specification refers throughout to computational and networkenvironments that include virtual machines (VMs). However, virtualmachines are merely one example of data compute nodes (DCNs) or datacompute end nodes, also referred to as addressable nodes. DCNs mayinclude non-virtualized physical hosts, virtual machines, containersthat run on top of a host operating system without the need for ahypervisor or separate operating system, and hypervisor kernel networkinterface modules.

VMs, in some embodiments, operate with their own guest operating systemson a host using resources of the host virtualized by virtualizationsoftware (e.g., a hypervisor, virtual machine monitor, etc.). The tenant(i.e., the owner of the VM) can choose which applications to operate ontop of the guest operating system. Some containers, on the other hand,are constructs that run on top of a host operating system without theneed for a hypervisor or separate guest operating system. In someembodiments, the host operating system uses name spaces to isolate thecontainers from each other and therefore provides operating-system levelsegregation of the different groups of applications that operate withindifferent containers. This segregation is akin to the VM segregationthat is offered in hypervisor-virtualized environments that virtualizesystem hardware, and thus can be viewed as a form of virtualization thatisolates different groups of applications that operate in differentcontainers. Such containers are more lightweight than VMs.

Hypervisor kernel network interface modules, in some embodiments, arenon-VM DCNs that include a network stack with a hypervisor kernelnetwork interface and receive/transmit threads. One example of ahypervisor kernel network interface module is the vmknic module that ispart of the ESXi™ hypervisor of VMware, Inc.

It should be understood that while the specification refers to VMs, theexamples given could be any type of DCNs, including physical hosts, VMs,non-VM containers, and hypervisor kernel network interface modules. Infact, the example networks could include combinations of different typesof DCNs in some embodiments.

While the invention has been described with reference to numerousspecific details, one of ordinary skill in the art will recognize thatthe invention can be embodied in other specific forms without departingfrom the spirit of the invention. In addition, a number of the figures(including FIGS. 12, 16, 20, and 23) conceptually illustrate processes.The specific operations of these processes may not be performed in theexact order shown and described. The specific operations may not beperformed in one continuous series of operations, and different specificoperations may be performed in different embodiments. Furthermore, theprocess could be implemented using several sub-processes, or as part ofa larger macro process. Thus, one of ordinary skill in the art wouldunderstand that the invention is not to be limited by the foregoingillustrative details, but rather is to be defined by the appendedclaims.

1. For a network management and control system that manages a virtualinfrastructure deployed across a set of datacenters, a methodcomprising: based on input from a top-level user of the virtualinfrastructure, (i) deploying a first logical network within the virtualinfrastructure and (ii) defining a set of one or more second-level usersof the virtual infrastructure, wherein the top-level user exposesentities of the first logical network to the set of second-level usersvia labels that provide information to the set of second-level usersabout the exposed entities of the first logical network without enablingthe set of second-level users to view the configuration of the firstlogical network entities; receiving input from a particular second-leveluser of the virtual infrastructure to define a second logical networkand connect the second logical network to the first logical network,wherein the first and second logical networks use a same data model andwherein the set of second-level users is restricted from viewingconfiguration of the first logical network.
 2. The method of claim 1,wherein the top-level user is an administrator for a provider of thevirtual infrastructure and the set of second-level users includesadministrators for tenants of the virtual infrastructure.
 3. The methodof claim 2, wherein the provider of the virtual infrastructure is anenterprise IT team and the tenants comprise different sections of abusiness of the enterprise.
 4. For a network management and controlsystem that manages a virtual infrastructure deployed across a set ofdatacenters, a method comprising: based on input from a top-level userof the virtual infrastructure, (i) deploying a first logical networkwithin the virtual infrastructure and (ii) defining a set of one or moresecond-level users of the virtual infrastructure; receiving input from aparticular second-level user of the virtual infrastructure to define asecond logical network and connect the second logical network to thefirst logical network, wherein the first and second logical networks usea same data model and wherein the set of second-level users isrestricted from viewing configuration of the first logical network;receiving input from the particular second-level user of the virtualinfrastructure to create accounts for a set of one or more third-levelusers of the virtual infrastructure, wherein the set of third-levelusers of the virtual infrastructure is enabled to define logicalnetworks that connect to one or more of the first and second logicalnetworks.
 5. The method of claim 4, wherein the set of third-level usersis restricted from viewing configurations for the first and secondlogical networks as well as the logical networks of other third-levelusers.
 6. The method of claim 4, wherein the logical networks defined bythe set of third-level users uses the same data model as the first andsecond logical networks.
 7. The method of claim 4, wherein the secondlogical network is deployed within a first virtual cloud, wherein atleast one of the third-level users defines a third logical networkwithin a second virtual cloud.
 8. The method of claim 7, wherein thevirtual clouds provide isolation from other logical networks within thevirtual infrastructure.
 9. (canceled)
 10. The method of claim 1, whereinthe exposed entities comprise a logical router that providesconnectivity to external networks, wherein the particular second-leveluser connects a logical router of the second logical network to theexposed logical router in order to provide connectivity to the externalnetworks for data compute nodes (DCNs) of the second logical network.11. The method of claim 10, wherein the exposed entities comprise aparticular virtual routing and forwarding (VRF) table of the logicalrouter of the first logical network that provides connectivity toexternal networks.
 12. The method of claim 1, wherein the exposedentities comprise a security group, wherein the particular second-leveluser defines firewall rules for the second logical network using thesecurity group such that the firewall rules apply to DCNs of the secondlogical network that belong to the security group.
 13. The method ofclaim 1, wherein the exposed entities comprise a physical infrastructureentity.
 14. The method of claim 1, wherein the top-level user is enabledto view and configure physical infrastructure entities that are hiddenfrom the set of second-level users.
 15. For a network management andcontrol system that manages a virtual infrastructure deployed across aset of datacenters, a method comprising: based on input from a top-leveluser of the virtual infrastructure, (i) deploying a first logicalnetwork within the virtual infrastructure and (ii) defining a set of oneor more second-level users of the virtual infrastructure; receivinginput from a particular second-level user of the virtual infrastructureto define a second logical network and connect the second logicalnetwork to the first logical network, wherein the first and secondlogical networks use a same data model and wherein the set ofsecond-level users is restricted from viewing configuration of the firstlogical network; wherein the top-level user is enabled to view andconfigure physical infrastructure entities that are hidden from the setof second-level users; wherein the logical network definitions arestored as policy trees, wherein the policy tree for the first logicalnetwork comprises physical infrastructure nodes defining the physicalinfrastructure of different sites, wherein the policy tree for thesecond logical network is restricted from comprising any physicalinfrastructure nodes.
 16. A non-transitory machine-readable mediumstoring a network manager program which when executed by at least oneprocessing unit manages a virtual infrastructure deployed across a setof datacenters, the network manager program comprising sets ofinstructions for: based on input from a top-level user of the virtualinfrastructure, (i) deploying a first logical network within the virtualinfrastructure and (ii) defining a set of one or more second-level usersof the virtual infrastructure, wherein the top-level user exposesentities of the first logical network to the set of second-level usersvia labels that provide information to the set of second-level usersabout the exposed entities of the first logical network without enablingthe set of second-level users to view the configuration of the firstlogical network entities; receiving input from a particular second-leveluser of the virtual infrastructure to define a second logical networkand connect the second logical network to the first logical network,wherein the first and second logical networks use a same data model andwherein the set of second-level users is restricted from viewingconfiguration of the first logical network.
 17. The non-transitorymachine-readable medium of claim 16, wherein the top-level user is anadministrator for a provider of the virtual infrastructure and the setof second-level users includes administrators for tenants of the virtualinfrastructure.
 18. A non-transitory machine-readable medium storing anetwork manager program which when executed by at least one processingunit manages a virtual infrastructure deployed across a set ofdatacenters, the network manager program comprising sets of instructionsfor: based on input from a top-level user of the virtual infrastructure,(i) deploying a first logical network within the virtual infrastructureand (ii) defining a set of one or more second-level users of the virtualinfrastructure; receiving input from a particular second-level user ofthe virtual infrastructure to define a second logical network andconnect the second logical network to the first logical network, whereinthe first and second logical networks use a same data model and whereinthe set of second-level users is restricted from viewing configurationof the first logical network; receiving input from the particularsecond-level user of the virtual infrastructure to create accounts for aset of one or more third-level users of the virtual infrastructure; theset of third-level users of the virtual infrastructure is enabled todefine logical networks that connect to one or more of the first andsecond logical networks; and the logical networks defined by the set ofthird-level users uses the same data model as the first and secondlogical networks.
 19. The non-transitory machine-readable medium ofclaim 18, wherein: the second logical network is deployed within a firstvirtual cloud; and at least one of the third-level users defines a thirdlogical network within a second virtual cloud, wherein the virtualclouds provide isolation from other logical networks within the virtualinfrastructure.
 20. (canceled)
 21. A non-transitory machine-readablemedium storing a network manager program which when executed by at leastone processing unit manages a virtual infrastructure deployed across aset of datacenters, the network manager program comprising sets ofinstructions for: based on input from a top-level user of the virtualinfrastructure, (i) deploying a first logical network within the virtualinfrastructure and (ii) defining a set of one or more second-level usersof the virtual infrastructure; receiving input from a particularsecond-level user of the virtual infrastructure to define a secondlogical network and connect the second logical network to the firstlogical network, wherein the first and second logical networks use asame data model and wherein the set of second-level users is restrictedfrom viewing configuration of the first logical network; wherein thetop-level user is enabled to view and configure physical infrastructureentities that are hidden from the set of second-level users; the logicalnetwork definitions are stored as policy trees; the policy tree for thefirst logical network comprises physical infrastructure nodes definingthe physical infrastructure of different sites; and the policy tree forthe second logical network is restricted from comprising any physicalinfrastructure nodes.